MONDAY, June 3 (HealthDay News) -- A new study adds to the growing body of evidence that a healthy lifestyle will not only protect your heart health but also reduce your risk of death.

Regular exercise, eating a healthy diet and maintaining a healthy weight all have clear health benefits, but the most significant lifestyle change people can make to protect their health is to stop smoking, researchers from Johns Hopkins University School of Medicine report.

"Of all the lifestyle factors, we found that smoking avoidance played the largest role in reducing the risk of coronary heart disease and mortality," study senior author Dr. Roger Blumenthal, a cardiologist and professor of medicine at the School of Medicine, said in a university news release. "Smokers who adopted two or more of the healthy behaviors still had lower survival rates after 7.6 years than did nonsmokers who were sedentary and obese."

The study, published online June 3 in the American Journal of Epidemiology, involved more than 6,200 men and women ranging in age from 44 to 84. The participants, who were white, black, Hispanic or Chinese, were followed for an average of almost eight years. Each underwent a coronary calcium screening using a CT scan when the study began, to check for early signs of calcium deposits, which could increase their risk for heart attack. Over the course of the study, they were re-assessed to determine if they had suffered a heart attack, sudden cardiac arrest or chest pain or had undergone angioplasty. The researchers also tracked deaths from heart disease or other causes.

Aside from the benefits of avoiding tobacco, the researchers found that exercising regularly, maintaining a healthy weight and adopting a Mediterranean-style diet -- one rich in produce, fish, nuts and whole grains -- helped prevent the early buildup of calcium deposits in the arteries. These lifestyle changes also reduced the risk of death by 80 percent over the course of eight years.

The researches assigned each participant a lifestyle score from zero to four, with four being the healthiest. This rating system was based on diet, body-mass index (BMI), level of physical activity and smoking. Only 2 percent of the participants met all four healthy lifestyle criteria.

"While there are risk factors that people can't control, such as their family history and age, these lifestyle measures are things that people can change and consequently make a big difference in their health. That's why we think this is so important," said lead author Dr. Haitham Ahmed, an internal medicine resident with Hopkins' Ciccarone Center for the Prevention of Heart Disease.

The researchers say their findings underscore recent American Heart Association recommendations advising people to quit smoking and stick to a diet rich in vegetables, fruits, nuts, whole grains and fish, while being active and maintaining a BMI of less than 25. BMI is a measurement of body fat based on height and weight.